Tiagaine (Gabitril - Abbot), a gamma-aminobutyric acid (GABA) uptake inhibitor, has been approved by the FDA for oral use as an adjunct to other drugs for treatment of partial seizures in patients more than 12 years old. Since most adult patients with resistant epilepsy have partial seizures, new antiepileptic drugs are usually tried first for this indictation.

Zonisamide (Zonegran - Elan Pharma), a sulfonamide chemically unrelated to other antiepileptic drugs, has been approved by the FDA for adjunctive use in adults with partial seizures. Zonisamide has been available in Japan for more than 10 years.

Oxcarbazepine, which is chemically similar to carbamazepine, and levetiracetam, a pyrrolidine acetamide chemically unrelated to other antiepileptic drugs, are the sixth and seventh drugs approved by the US Food and Drug Administration in the last five years for oral use in partial seizures.

Anticonvulsants are now widely used for treatment of psychiatric illnesses, particularly bipolar disorder. Lithium is the standard drug for treatment of bipolar disorder, but it can cause severe toxicity, serum concentrations must be monitored, and it is not effective in some patients.

When used for the appropriate seizure type, antiseizure medications (ASMs) are roughly equivalent in efficacy. In addition to the seizure type, the choice of drug is usually based on factors such as ease of use, spectrum of activity, adverse effects, interactions with other drugs, presence of comorbid conditions, suitability for elderly persons and those with childbearing potential, and cost. Treatment should begin with a single drug, increasing the dosage gradually until seizures are controlled or adverse effects become unacceptable. If seizures persist, expert clinicians generally...